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G4 Quicksilver Power Supply Woes

Phipli

Well-known member
Afternoon folks, I'm not used to this fancy "modern" corner of the forum. Perhaps I should claim it is a QuickPlatinum G4?

My Quicksilver 800MHz Single (2002?) seems to be having power supply woes. I've pulled out all but a couple of small, hard to reach caps and tested them out of circuit (seriously, like 20, one at a time) and they're all close to spec.

Despite this, when I power it on, it starts, bongs... waits a (variable) few seconds, then powers itself off. There is possibly a faint ticking sound, like a mouse tapping out morse code on the pipes in their plumbing.

I've watched for a confirmed working PSU on (UK) eBay, but haven't seen one at a reasonable price and suspect I won't, so am considering going the ATX mod route. Does anybody have power supply suggestions for one that would fit nicely? Any tips to make my life as easy as possible?

I'm comfortable with hacking, competent at soldering and hand tools etc. so not worried about getting stuck in. My reluctance up to this point was purely originality give this is an exceptionally well looked after machine.

Gratuitous photos, missing bits are in the other room from when I had the PSU in bits.
 

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cheesestraws

Well-known member
Despite this, when I power it on, it starts, bongs... waits a (variable) few seconds, then powers itself off. There is possibly a faint ticking sound, like a mouse tapping out morse code on the pipes in their plumbing.

When it ticks, if you turn it off at the mains and then after a second turn it back on, does it keep ticking, or does it start up again? i.e. is it possible it's thermal, or is it definitely electrical?
 

Phipli

Well-known member
PS I also repasted it, just incase it was the CPU getting hot... then I replaced the CPU card since I had it in bits and the symptoms are identical.

Just now it is 1.2GHz and doesn't work.

I also previously tried another GPU and removed all but one RAM stick, then swapped in another one RAM stick. I've also tried with a new battery.

I haven't zapped my PRAM :p but given I've had the battery out :)
 

Phipli

Well-known member
When it ticks, if you turn it off at the mains and then after a second turn it back on, does it keep ticking, or does it start up again? i.e. is it possible it's thermal, or is it definitely electrical?
It stops ticking when it turns itself off and doesn't before powered on... does that cover what you're thinking? Or do you have something else in mind? I'd have to cut the power before it turns itself off and then power it on on the front again.
 

Phipli

Well-known member
Also I wouldn't assume the ticking is definitely relevant - you wouldn't notice if you weren't intentionally listening with your head in the case. But it might be.
 

cheesestraws

Well-known member
It stops ticking when it turns itself off and doesn't before powered on... does that cover what you're thinking? Or do you have something else in mind? I'd have to cut the power before it turns itself off and then power it on on the front again.

I'm trying to work out whether if you power it back on before something cools down, does it keep being in the broken state or not? :)
 

Phipli

Well-known member
It powers on as many times as you dare without cycling the mains switch.
 
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herd

Well-known member
I doubt it's the power supply. If you can't measure the voltages in a few seconds before it shuts off you can ground the green wire and check all the voltages. Is it set for 120 or 240 as appropriate?

Try a PMU reset with a good battery.

That looks like a sonnet CPU. Do you have a stock one you could try? Are the CPU connectors damaged? Those little gold pins are easily bent or contaminated with dust/crud when swapping CPU cards.
 

Phipli

Well-known member
I doubt it's the power supply. If you can't measure the voltages in a few seconds before it shuts off you can ground the green wire and check all the voltages. Is it set for 120 or 240 as appropriate?

Try a PMU reset with a good battery.

That looks like a sonnet CPU. Do you have a stock one you could try? Are the CPU connectors damaged? Those little gold pins are easily bent or contaminated with dust/crud when swapping CPU cards.
Afternoon,
I put the Sonnet in myself about 2 hours ago, it was an 800MHz single and showing identical symptoms this morning. I switched it out since I had it, just in case it was the CPU.
 

Phipli

Well-known member
Is it set for 120 or 240 as appropriate?

Try a PMU reset with a good battery.
There isn't a manual voltage switch on this one, unless its hidden. Its a 100-240V~ supply.

Tried pressing the PMU button for 3 seconds after installing a battery from my pack of new ones - no change.

I haven't tested the voltages - I can have a look tomorrow.
 

herd

Well-known member
The switch is right beside the socket for the power cord on the ones I've seen. Maybe they're different in the UK.

I saw one where a loose screw got dropped thru the gap behind the logic board and was causing havoc between the metal case and the logic board.
 

ried

Well-known member
I had the exact same symptoms with the faint ticking and the fan under the power supply moving ever so slightly with each tick. I replaced the power supply and the problem went away. Part number API1PC12 / Apple part number 614-0157 in case it helps the search. Here's the least expensive one I currently see on eBay:

 

Phipli

Well-known member
I had the exact same symptoms with the faint ticking and the fan under the power supply moving ever so slightly with each tick.
Hotwired mine on the bench (dining room table) and its doing the exact same thing with the fan. In the case all the external fans spun up.

Wish I was better at powersupplies.
 
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